<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <form>
        宽度:<input id="width" type="text" />
    </form>
    <form>
        高度:<input id="height" type="text" />
    </form>
    <form>
        <input id="calculate" type="button" value="计算"/>
    </form>
    <form>
        周长<input id="perimeter" type="text" />
    </form>
    <form>
        面积:<input id="area" type="text" />
    </form>
</body>
</html>